CA1070765A - Current measuring apparatus - Google Patents
Current measuring apparatusInfo
- Publication number
- CA1070765A CA1070765A CA277,666A CA277666A CA1070765A CA 1070765 A CA1070765 A CA 1070765A CA 277666 A CA277666 A CA 277666A CA 1070765 A CA1070765 A CA 1070765A
- Authority
- CA
- Canada
- Prior art keywords
- supply
- conductors
- load
- conductor
- energising
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/20—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices
- G01R15/202—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using galvano-magnetic devices, e.g. Hall-effect devices, i.e. measuring a magnetic field via the interaction between a current and a magnetic field, e.g. magneto resistive or Hall effect devices using Hall-effect devices
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Measuring Magnetic Variables (AREA)
- Transformers For Measuring Instruments (AREA)
Abstract
PHB. 32,548.
ABSTRACT
An apparatus for producing a signal representative of the sum of the currents flowing in conductors of a poly-phase electrical supply to a load contains a magnetic circuit in which is positioned a magneto-sensitive device. An individual energizing conductor for the magnetic circuit is provided for each conductor of the polyphase supply and a rectifier arrangement is connected so as to feed each of these energizing conductors with a unidirectional current which is a measure of the current flowing in the corresponding conductor of the supply in a given direction relative to the load, this direction being the same of all conductors of the supply. The unidirectional currents have a polarity such that the magnetic fields which are produced in the magnetic circuit will assist each other.
ABSTRACT
An apparatus for producing a signal representative of the sum of the currents flowing in conductors of a poly-phase electrical supply to a load contains a magnetic circuit in which is positioned a magneto-sensitive device. An individual energizing conductor for the magnetic circuit is provided for each conductor of the polyphase supply and a rectifier arrangement is connected so as to feed each of these energizing conductors with a unidirectional current which is a measure of the current flowing in the corresponding conductor of the supply in a given direction relative to the load, this direction being the same of all conductors of the supply. The unidirectional currents have a polarity such that the magnetic fields which are produced in the magnetic circuit will assist each other.
Description
PIIB ~25l~8 ~J.
25.3.77 ~C97~7~5 "Current measuring apparatus".
This invention relates to apparatus for producing a signal representative of current flow-ing in an a.c. electrical supply.
It is known to use a Hall element to pro-duce an output voltage proportional to current in an electric circuit by positioning the Hall element in a magne-tic circuit which is providecl with an energising winding. If the current is passed through the energising winding and the HCL11 e1ement iS SUP-plied wi-th a steady current a Hall voltage which is proportional to the nnagnetic field at the ele-men-t and hence to the current flowing through the energising winding will be set up at the Elall ele-ment, Such an arrangement can provide elec~rical isolation between the input current and the output~
voltage, which ~s sometimes an advantage.
It is sometimes required to produce a signal which is representative of the sum of the moduli of the currents flowing in the conductors of a polyphase electrical supply to a load, and it is an object of the invention to provide ap-paratus by which this can be done.
The invention provides apparatus fo~ pro- ¦
ducing a signal representative of the sum of the I' . .~...... ' .
25.3.77 ~7~7~5 moduli of the currents flowing in conductors of a polyphase electrical supply to a load, comprising a magnetic circuit in which is positioned a mag-neto-sensitive device, an individual energising conductor for said magnetic circuit corresponding to each said conductor of the supply~ and rectifier means for feeding each said energising conductor with a unidirectional current which is a measure of the curren-t flowing in the corresponding con-ductor of the supply in a given direction relative to the load, which given direction is the same for all said conductors of the supply, said unidirec-tional currents having a polarity such that the magnetic fields which result in the magnetic cir-cuit will assist each other, Such an arrangement can provide electri-cal isolation bo-th between the various energising conductors themselves and between each said ener-gising conductor and the output signal ~which may Z0 be produced by a Hall element). If the load is balanced three-phase and each energizing conduc-tor is in the form of a winding on a common yoke - of magnetic material 9 construction of these wind-ings to be substantially identical can result in substantially identical contributions from each to the output signal, which can be an advantage compared ~5ith conventional method~ of producing ;
PHB 32~48 25.3.77 3q6~
a signal representati~e of the moduli of` the currents flowing in the conductors of a polyphase supply, in which it is often difficult to correctly balance the various contributions.
It is, of course, necessary to provide rec-tifier means to supply each energizing conductor with an unidirectional current because the algebraic sum of the currents in the phase conductors of a poly-phase supply is at all times zero (assuming there is no neutral connection).
~n embodiment of the invention will now be described, by way of example, with reference to the accornpanying diagrammatic drawing.
In the drawing a three-phase load 1, for e~ample an asynchronous electric motor, is supplied from terminals 2, 3 and 4 of a three-phase elec-trical supply. The series combination of a rec-tifier 5 and a winding 6, which series combina-tion is shunted by an oppositely poled rectifler 7, is included in the connection between the ter-~inal 2 and the load 1. Similarly the series com-bination of a rectifier 8 and a winding 9~ which series combination is shunted by an oppositely poled rectifier 10, is included in the connection between the terminal 3 and the load 1, and the series combination of a rectifier 11 and a winding 12, which series combination is shunted by an oppositely poled ... . .
25.3.77 ~7V7~5 rectifier 13, is included in the connection between the termlnal Ll and the load 1. Windings 6, 9 and 12 are identical and are wound on a yoke 19 of magnetic material, for example a ferrite. They constitute energising windings for the magnetic circuit de-fined by the yoke i9, which circuit has a gap 14 in which is situated a Hall element 15. Element 15 is provided with a steady operating current from a source 16 and has Hall voltage output ter-minals 17 and 18.
~t will be seen that currents flowing in the oonventional direction from terminals 2, 3 and 4 to the load 1 will flow through the series com-binations 5 and 6, 8 and 9, and 11 and 12 respec-tively, whereas currents flowing in the opposite direction will flow through ~ectifiers 7, 10 and 13 respectively. Thus each pair of rectifiers 5 and 7, 8 and 10, and l1 and 13 causes the corres-ponding winding 6, 9 or 12 to be supplied with a unidirectional current which is equal to the cur-rent flowing from the corresp~onding terminal 2, 3 or l~ to the load 1.
The wlndings 6, 9 and 12 (which may in - practice be concentric) are wound in a sense such that the resultlng magnetlc fields produced there-by in the yoke 19 and hence at the ~all element 15 assist one another. Element 15 thus experiences P~I~ 325l~
25.3.77 ~.~37~76~
a magnetic field which is a measure of the sum of the moduli of the currents flowing in the conductors connecting the terminals 2, 3 and 4 to the load 1.
(Because a "three-wire" load is used with a three phase supply all possible currents are detected~
any current flowing through the rectifier 7 at any time is matched by a corresponding current o~ cur-rents flowing through the series combination 8, 9 and/or the series combination 11, 12, and a simi-lar situation exis~s with any currents flowing through the rectifiers 10 and 13)~ The ~Iall voltage appearing across terminals 17 and 18, the ripple frequency of which is six times the supply fre-quency; is therefore also a measure of the sum of the moduli of said currents.
If desiredj Hall element 15 may be re-placed by a magneto-sensitive element of another kind~ for example a magneto-resistive element.
It will be evident that a similar ar-rangement may be used when the number of phases of the polyphase supply is different from three 9 the number of windings on the yolce 19 and their associated pairs of rectifiers at all times be-ing chosen to match the number of supply conduc-~5 tors the current in which it is desired to measure.
The number of turns in each winding will, of course, be chosen to obtain the sensitivity re-25.3.~7 ~o7G5 quired with the apparatus; provision o~ an exces-sive number of turns will not normally be desirable in view of` the series inductance inevitably produced thereby (although the presence of the air gap 14 will make the series inductance smaller than it would otherwise be~.
The rectifiers 7, 10 and 13 may be re-placed by low-value resistors, if desired.
The star-connected load. 1 may be of course be replaced by a delta-conrlected load if clesired~
.
25.3.77 ~C97~7~5 "Current measuring apparatus".
This invention relates to apparatus for producing a signal representative of current flow-ing in an a.c. electrical supply.
It is known to use a Hall element to pro-duce an output voltage proportional to current in an electric circuit by positioning the Hall element in a magne-tic circuit which is providecl with an energising winding. If the current is passed through the energising winding and the HCL11 e1ement iS SUP-plied wi-th a steady current a Hall voltage which is proportional to the nnagnetic field at the ele-men-t and hence to the current flowing through the energising winding will be set up at the Elall ele-ment, Such an arrangement can provide elec~rical isolation between the input current and the output~
voltage, which ~s sometimes an advantage.
It is sometimes required to produce a signal which is representative of the sum of the moduli of the currents flowing in the conductors of a polyphase electrical supply to a load, and it is an object of the invention to provide ap-paratus by which this can be done.
The invention provides apparatus fo~ pro- ¦
ducing a signal representative of the sum of the I' . .~...... ' .
25.3.77 ~7~7~5 moduli of the currents flowing in conductors of a polyphase electrical supply to a load, comprising a magnetic circuit in which is positioned a mag-neto-sensitive device, an individual energising conductor for said magnetic circuit corresponding to each said conductor of the supply~ and rectifier means for feeding each said energising conductor with a unidirectional current which is a measure of the curren-t flowing in the corresponding con-ductor of the supply in a given direction relative to the load, which given direction is the same for all said conductors of the supply, said unidirec-tional currents having a polarity such that the magnetic fields which result in the magnetic cir-cuit will assist each other, Such an arrangement can provide electri-cal isolation bo-th between the various energising conductors themselves and between each said ener-gising conductor and the output signal ~which may Z0 be produced by a Hall element). If the load is balanced three-phase and each energizing conduc-tor is in the form of a winding on a common yoke - of magnetic material 9 construction of these wind-ings to be substantially identical can result in substantially identical contributions from each to the output signal, which can be an advantage compared ~5ith conventional method~ of producing ;
PHB 32~48 25.3.77 3q6~
a signal representati~e of the moduli of` the currents flowing in the conductors of a polyphase supply, in which it is often difficult to correctly balance the various contributions.
It is, of course, necessary to provide rec-tifier means to supply each energizing conductor with an unidirectional current because the algebraic sum of the currents in the phase conductors of a poly-phase supply is at all times zero (assuming there is no neutral connection).
~n embodiment of the invention will now be described, by way of example, with reference to the accornpanying diagrammatic drawing.
In the drawing a three-phase load 1, for e~ample an asynchronous electric motor, is supplied from terminals 2, 3 and 4 of a three-phase elec-trical supply. The series combination of a rec-tifier 5 and a winding 6, which series combina-tion is shunted by an oppositely poled rectifler 7, is included in the connection between the ter-~inal 2 and the load 1. Similarly the series com-bination of a rectifier 8 and a winding 9~ which series combination is shunted by an oppositely poled rectifier 10, is included in the connection between the terminal 3 and the load 1, and the series combination of a rectifier 11 and a winding 12, which series combination is shunted by an oppositely poled ... . .
25.3.77 ~7V7~5 rectifier 13, is included in the connection between the termlnal Ll and the load 1. Windings 6, 9 and 12 are identical and are wound on a yoke 19 of magnetic material, for example a ferrite. They constitute energising windings for the magnetic circuit de-fined by the yoke i9, which circuit has a gap 14 in which is situated a Hall element 15. Element 15 is provided with a steady operating current from a source 16 and has Hall voltage output ter-minals 17 and 18.
~t will be seen that currents flowing in the oonventional direction from terminals 2, 3 and 4 to the load 1 will flow through the series com-binations 5 and 6, 8 and 9, and 11 and 12 respec-tively, whereas currents flowing in the opposite direction will flow through ~ectifiers 7, 10 and 13 respectively. Thus each pair of rectifiers 5 and 7, 8 and 10, and l1 and 13 causes the corres-ponding winding 6, 9 or 12 to be supplied with a unidirectional current which is equal to the cur-rent flowing from the corresp~onding terminal 2, 3 or l~ to the load 1.
The wlndings 6, 9 and 12 (which may in - practice be concentric) are wound in a sense such that the resultlng magnetlc fields produced there-by in the yoke 19 and hence at the ~all element 15 assist one another. Element 15 thus experiences P~I~ 325l~
25.3.77 ~.~37~76~
a magnetic field which is a measure of the sum of the moduli of the currents flowing in the conductors connecting the terminals 2, 3 and 4 to the load 1.
(Because a "three-wire" load is used with a three phase supply all possible currents are detected~
any current flowing through the rectifier 7 at any time is matched by a corresponding current o~ cur-rents flowing through the series combination 8, 9 and/or the series combination 11, 12, and a simi-lar situation exis~s with any currents flowing through the rectifiers 10 and 13)~ The ~Iall voltage appearing across terminals 17 and 18, the ripple frequency of which is six times the supply fre-quency; is therefore also a measure of the sum of the moduli of said currents.
If desiredj Hall element 15 may be re-placed by a magneto-sensitive element of another kind~ for example a magneto-resistive element.
It will be evident that a similar ar-rangement may be used when the number of phases of the polyphase supply is different from three 9 the number of windings on the yolce 19 and their associated pairs of rectifiers at all times be-ing chosen to match the number of supply conduc-~5 tors the current in which it is desired to measure.
The number of turns in each winding will, of course, be chosen to obtain the sensitivity re-25.3.~7 ~o7G5 quired with the apparatus; provision o~ an exces-sive number of turns will not normally be desirable in view of` the series inductance inevitably produced thereby (although the presence of the air gap 14 will make the series inductance smaller than it would otherwise be~.
The rectifiers 7, 10 and 13 may be re-placed by low-value resistors, if desired.
The star-connected load. 1 may be of course be replaced by a delta-conrlected load if clesired~
.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for producing a signal represen-tative of the sum of the moduli of the currents flowing in conductors of a polyphase electrical supply to a load, comprising a magnetic circuit in which is positioned a magneto-sensitive device, an individual energising conductor for said mag-netic circuit corresponding to each said conduc-tor of the supply, and rectifier means for feed-ing each said energising conductor with a uni-directional current which is a measure of the cur-rent flowing in the corresponding conductors of the supply in a given direction relative to the load, which given direction is the same for all said conductors of the supply, said unidirectional currents having a polarity such that the magnetic fields which result in the magnetic circuit will assist each other.
2. Apparatus as claimed in Claim 1, wherein the magneto-sensitive device is a Hall element.
3. Apparatus as claimed in Claim 1 or Claim 2,wherein each said rectifier means comprises a first rectifier element in series with the corresponding energising conduc-tor and a second rectifier element in parallel with the resulting series combination, the second rec-PHB. 32,548.
tifier element being oppositely poled to the first rectifier element.
tifier element being oppositely poled to the first rectifier element.
4. Apparatus as claimed in Claim 1 or 2, wherein each energising conductor is in the form of a winding on a common yoke of magnetic material, said windings being sub-stantially identical.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB19111/76A GB1488775A (en) | 1976-05-10 | 1976-05-10 | Current measuring apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1070765A true CA1070765A (en) | 1980-01-29 |
Family
ID=10123961
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA277,666A Expired CA1070765A (en) | 1976-05-10 | 1977-05-04 | Current measuring apparatus |
Country Status (10)
| Country | Link |
|---|---|
| US (1) | US4160950A (en) |
| JP (1) | JPS52137383A (en) |
| CA (1) | CA1070765A (en) |
| DE (1) | DE2719703A1 (en) |
| DK (1) | DK199177A (en) |
| FR (1) | FR2351416A1 (en) |
| GB (1) | GB1488775A (en) |
| IT (1) | IT1079002B (en) |
| SE (1) | SE7705276L (en) |
| ZA (1) | ZA772584B (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3130277A1 (en) * | 1981-07-31 | 1983-02-17 | Vacuumschmelze Gmbh, 6450 Hanau | MAGNETIC CORE MADE OF SOFT MAGNETIC MATERIAL FOR A CURRENT SENSOR WITH A MAGNETIC-DEPENDENT SEMICONDUCTOR ELEMENT FOR DETECTING DC AND AC CURRENTS |
| US4525669A (en) * | 1982-12-20 | 1985-06-25 | Sangamo Weston, Inc. | Power measurement in an electrical distribution system having three or more wires |
| US4717872A (en) * | 1985-01-28 | 1988-01-05 | Watt Watcher Inc. | Device for monitoring consumption of electrical power |
| GB8800845D0 (en) * | 1988-01-14 | 1988-02-17 | Yorkshire Water Authority | Galvanic isolator |
| US6429639B1 (en) * | 1997-01-21 | 2002-08-06 | International Rectifier Corporation | Combined filter inductor and hall current sensor |
| KR100448311B1 (en) * | 2002-04-11 | 2004-09-16 | 이규대 | current measurement apparatus |
| US7043380B2 (en) | 2003-09-16 | 2006-05-09 | Rodenberg Iii Ernest Adolph | Programmable electricity consumption monitoring system and method |
| US7459900B2 (en) * | 2006-02-03 | 2008-12-02 | Bae Systems Land & Armaments L.P. | Modular current sensor for modularized servo control system |
| US7847536B2 (en) * | 2006-08-31 | 2010-12-07 | Itron, Inc. | Hall sensor with temperature drift control |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE373058C (en) * | 1923-04-07 | Siemens & Halske Akt Ges | Measuring device for determining the components of an alternating current running in different directions | |
| US851149A (en) * | 1904-11-21 | 1907-04-23 | Gen Electric | Leakage-indicator for high-tension lines. |
| US1257514A (en) * | 1915-08-23 | 1918-02-26 | William Meyer | Electrical measuring instrument. |
| FR682187A (en) * | 1928-09-26 | 1930-05-23 | Siemens Ag | Method for controlling electrical connecting, measuring or indicating devices |
| DE1014646B (en) * | 1954-11-10 | 1957-08-29 | Siemens Ag | Device for measuring the earth unbalance work in three-phase networks |
| FR1270405A (en) * | 1960-10-17 | 1961-08-25 | Brown | Device for drawing an alternating current at constant voltage from a conductor carrying a current |
-
1976
- 1976-05-10 GB GB19111/76A patent/GB1488775A/en not_active Expired
-
1977
- 1977-04-29 ZA ZA00772584A patent/ZA772584B/en unknown
- 1977-05-03 DE DE19772719703 patent/DE2719703A1/en not_active Withdrawn
- 1977-05-04 CA CA277,666A patent/CA1070765A/en not_active Expired
- 1977-05-05 DK DK199177A patent/DK199177A/en unknown
- 1977-05-06 US US05/794,404 patent/US4160950A/en not_active Expired - Lifetime
- 1977-05-06 IT IT49315/77A patent/IT1079002B/en active
- 1977-05-06 SE SE7705276A patent/SE7705276L/en unknown
- 1977-05-09 JP JP5215477A patent/JPS52137383A/en active Pending
- 1977-05-10 FR FR7714212A patent/FR2351416A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| IT1079002B (en) | 1985-05-08 |
| JPS52137383A (en) | 1977-11-16 |
| FR2351416A1 (en) | 1977-12-09 |
| SE7705276L (en) | 1977-11-11 |
| DE2719703A1 (en) | 1977-11-24 |
| DK199177A (en) | 1977-11-11 |
| GB1488775A (en) | 1977-10-12 |
| US4160950A (en) | 1979-07-10 |
| ZA772584B (en) | 1978-12-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |